折半查找

#include <stdio.h>
#include <stdlib.h>

//先进行排序,在进行查找
void sort(int arr[10])
{
    int i,j,idx;
    for(i=0;i<9;i++)
    {
        idx =i;
        for(j=i+1;j<10;j++)
        {
            if(arr[idx]>arr[j])
                idx = j;
        }
        if(idx!=i)
        {
            int temp = arr[i];
            arr[i] = arr[idx];
            arr[idx] = temp;
        }
    }
}


int find(int *arr,int findData)
{
    int low=0,mid,high=9;
    int idx=-1;
    while(low<=high)
    {
        mid = (low+high)/2;

        if(arr[mid]==findData)
        {
            idx = mid;break;
        }

        //找的数比中间值小，不要了，包括中间值，变更最高位，减一除去了mid值
        else if(arr[mid]>findData)
            high = mid - 1;

        else if(arr[mid]<findData)
            low = mid + 1;

    }
    return idx;
}

void print(int arr[10])
{
    for(int i=0;i<10;i++)
    {
        printf("%d
",arr[i]);
    }
}

void main()
{
    int arr[10];
    int findData,idx;
    for(int i=0;i<10;i++)
    {
        arr[i] = rand()%100;
    }

    print(arr);
    sort(arr);
    putchar(10);
    print(arr);

    scanf("%d",&findData);
    idx = find(arr,findData);

    if(idx!=-1)
        printf("I find out,it's arr[%d]",idx);
    else 
        printf("sorry,I can't do it");
    system("pause");
}